Donald Trump campaigned as a fierce defender of the Second Amendment and the favored candidate of the National Rifle Association, vowing to undo any actions by President Barack Obama on gun control.

But when Trump nixed one of Obama’s most significant efforts to expand background checks on prospective gun buyers, he did so without fanfare. The Feb. 28 bill signing, which blocked the Social Security Administration from reporting mentally impaired recipients to a national background-check database, earned just a brief mention at the end of a White House advisory that contained no reference to firearms. Reporters ushered into the Oval Office that day heard Trump extol two other bills encouraging women to pursue careers in science.

Before Sunday’s mass shooting in Las Vegas, activists on both sides of the gun debate were focused on high-stakes legislation that would make it easier to buy gun silencers and to carry concealed weapons across state lines. That legislation has now stalled.

But, with less public attention, the Trump administration has eased some gun regulations in recent months. Among them: The Army Corps of Engineers has filed notice in a court case that it is reconsidering a ban on carrying firearms on its land; the Justice Department narrowed its definition of fugitives barred from purchasing weapons; and the Interior Department lifted a federal ban on hunting with lead ammunition in national parks.

A White House official denied any deliberate effort to play down the change to the background-checks policy and declined to comment on that change or others related to guns.

“It was very quiet because if anyone looks under the hood of these laws, they can recognize that this has caused a significant threat to public safety,” said David Chipman, senior policy adviser for the gun-control group Americans for Responsible Solutions and a former official with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). “If these laws were good laws supported by the public that protected people’s rights while ensuring public safety, they’d proudly talk about what they are.”

The catalyst for the Social Security rule was a law signed by President George W. Bush intended to upgrade background checks on gun buyers after 32 people were shot and killed at Virginia Tech in 2007. The shooter was able to buy firearms because his mental health record was never submitted to the National Instant Criminal Background Check System (NICS), a 19-year-old database that gun-control advocates say lacks reams of pertinent information.

The law prodded states and government agencies to step up reporting to NICS that would disqualify gun buyers because of their criminal records, immigration status or mental health problems. The Social Security Administration’s plan to identify an estimated 80,000 mentally impaired recipients incapable of managing their own finances was finalized a few days before Christmas in 2016. “Grandma Got Run Over by Obama,” the NRA’s political arm blasted in a riff on the novelty Christmas song. Gun rights groups have long fought efforts to improve the database, calling it federal overreach in the face of the Second Amendment.

One month into the Trump administration, the Republican-led Congress turned to a rarely used law that allows it to quickly unravel the prior president's last-minute regulations. The House and Senate revoked the Social Security rule, along with several environmental regulations imposed in the waning days of the Democratic administration. The move was opposed by gun-control advocates and cheered by an unusual coalition that included the NRA, the American Civil Liberties Union and some advocates for the mentally ill.

Some gun-control activists said they were not aware of the Trump bill-signing.

“He did it in the dark of night, as we say, with no announcement,” said Robin Lloyd of Americans for Responsible Solutions, the group founded by Gabrielle Giffords, the former Arizona congresswoman shot in the head while meeting with constituents in 2011.

Even less noticed was the Army Corps of Engineers’ decision to reconsider a Nixon-era gun policy prohibiting firearms, except for those used for hunting in some places, on lands and waters under Corps jurisdiction. The Corps is the nation’s largest administrator of outdoor recreation, administering 422 lake and river projects in 43 states and more than 4,500 miles of trails.

“In general, people who are carrying guns are safe and law-abiding and don’t become problematic just because they are on Army Corps of Engineers land,” said David Kopel, adjunct professor at Denver University’s Sturm College of Law and an analyst at the libertarian Cato Institute. “There’s been some progress under Trump in undoing or moderating anti-gun policies from anti-gun administrations.”

“It worries me to think about hunting and fishing becoming activities for the landowning elite,” Zinke, a former Montana congressman and an avid hunter and angler, said on March 2, his first day on the job.

Two weeks earlier, the Justice Department had issued a new definition of “fugitive” that allows more people with outstanding arrest warrants to legally buy guns. Under the revised rule, the FBI can block gun sales only to fugitives who have fled the states where their arrest warrant was issued. The change got little media coverage, though some law enforcement leaders raised concerns.

“Removing the people with warrants, you have to wonder if that’s putting guns in the hands of the people who maybe shouldn’t have them,” said Darrel Stephens, executive director of the Major Cities Chiefs Association.

The exact definition of a “fugitive” has long been a matter of debate. The FBI had a broad view of the term. But even before Trump took office, Justice Department officials sided with ATF, which argued that under federal law, gun purchases can be denied only for fugitives with arrest warrants who have fled across state lines. After Trump’s inauguration, justice officials narrowed that category further to those who have fled across state lines to avoid prosecution for a crime or to avoid giving testimony in a criminal proceeding.

Trump was the first sitting president to address the NRA since Ronald Reagan. The NRA spent more than $30 million boosting his campaign and attacking Democrat Hillary Clinton, more than any other outside group, according to the Center for Responsive Politics. NRA officials declined to comment on the administration’s recent actions on gun policy.

“You came through big for me, and I am going to come through for you,” Trump said at the NRA convention in April. “The eight-year assault on your Second Amendment freedoms has come to a crashing end.”

Obama fell far short of his goals on gun control, leaving a limited number of executive actions for his successor to overturn.

Congress rebuffed his push in 2013 to expand background checks to most gun sales and ban certain military-style assault rifles after 20 children and six adults were slain at a Newtown, Conn., elementary school. During his last year in office, Obama unveiled a broad package of more-incremental proposals to reduce gun violence, including money for mental health treatment, plans to sponsor research into “smart gun technology” and background checks for gun buyers using a trust or corporation to purchase some of the most dangerous weapons.

Chipman, of Americans for Responsible Solutions, called the package “meaningfully symbolic.” One of Obama’s most substantive proposals would have required gun sellers online and at gun shows to obtain federal licenses and conduct background checks. ATF did not receive additional funding, however, to expand its enforcement responsibilities. ATF officials said Tuesday they could not immediately comment.

In an early sign of the Trump administration’s posture on firearms, the second-highest-ranking official at ATF wrote a “white paper” — dated Jan. 20, the day of the inauguration — on loosening gun regulations. Ronald B. Turk, ATF associate deputy director and chief operating officer, called for lifting restrictions on sales of gun silencers, easing federal scrutiny of gun dealers who sell weapons later traced to crimes and reexamining the ban on importing assault weapons.

Three months later, Democrats on the House Oversight Committee grilled Turk.

“Do you represent the NRA?” demanded Rep. Gerald E. Connelly (D-Va.). “Or do you represent the American people at ATF? . . . I represent victims from Virginia Tech in my district. We buried six young people. And I couldn’t explain to them why an ATF agent or representative would think that legalizing silencers might be a good idea.”

Turk testified that he was gathering ideas for the new administration and that ATF should review its restrictions on armor-piercing ammunition.

“With the change in administration it was our impression that we . . . could expect a conversation about the regulations within the firearms industry,” he said.

Although the white paper boasted the ATF seal and listed Turk’s name and title, officials said it did not represent the views of the agency.

Beth ReinhardBeth Reinhard is a reporter on the investigative team at The Washington Post. She previously worked at the Wall Street Journal, National Journal, the Miami Herald and the Palm Beach Post. Follow

Sari HorwitzSari Horwitz covers the Justice Department, law enforcement and criminal justice issues nationwide for The Washington Post, where she has been a reporter for 33 years. Follow